This invention relates to magnetic conveyor belts in general and more particularly to an improved conveyor belt which permits reliably carrying objects whose main bulk does not lie in the plane of the conveyor belt.
One typical type of magnetic conveyor belt used in the prior art had disposed and spaced apart, in the belt supporting structure, two rail-like magnetic poles. These are poles of opposite polarity resulting in a magnetic field running therebetween and near the center of the belt. This type of arrangement has two disadvantages. In the first place, the magnetic field is concentrated in the center of the belt and secondary it is concentrated primarily in the plane of the belt. Another type of magnetic conveyor belt overcomes the first of these problems. In that known arrangement, the belt support comprises two side rails and a connecting plate with magnets fastened to the connecting plate having common pole rails situated between the flanges of the side rails. From a magnetic point of view, this construction differs from the first construction described above in that the belt support constitutes a portion of the magnetic field and consequently the magnetic field is distributed over the entire width of the conveyor surface and is not concentrated in the middle. However, this does not overcome the speed problem mentioned above. That is, the magnetic field is still concentrated in the plane of the belt. It is clear that in both of these previously known embodiments, the magnetic field is concentrated in the plane of the belt. As a result, articles which have the major portion of their mass lying in the plane of the belt such as pieces of flat iron will be strongly attracted by the magnetic field and will be securely held to the belt during conveyance. On the otherhand, articles having a bulk which lies primarily outside the plane of the belt will have the major portion of their mass outside the magnetic field and will not be so strongly attracted to the conveyor belt. As a result, these prior art conveyor belts are limited as to the types of objects which can be reliably transported.
It can thus be seen that there is a need for an improved type of magnetic conveyor belt which permits carrying different types of objects including flat objects and bulky objects in a manner such that they are firmly held in place on the belt.